Packing seals are well-known and used to prevent leakage around various movable machine parts, such as those in hydraulic pumps and the like.
The basic prior art packing seal is comprised of a series of individual rings which fit on top of one another when they are in place around the part to be sealed. Other prior art seals are of the spiral type, such as those shown in Gruber U.S. Pat. No. 567,233. These spiral seals are made of one continuous coiled piece and compress to seal the machine parts. In both cases, the inner diameter of the seal must be close to the outer diameter of the shaft or other machine part to be sealed in order to assure a tight fit and prevent leakage therebetween. Accordingly, the principal drawback of the prior art seals is that they are expensive to manufacture because different seal molds have to be made for seals of even slightly different diameter.
In an effort to overcome this drawback, some individual ring seals, i.e., the 8000 series from the A. W. Chesterton Company, the assignee herein, can be cut down so as to fit around parts having diameters somewhat smaller than that of the original ring. However, the cut away portion of the ring is wasted, and in any event, the ring cannot be made to fit parts having even a slightly greater diameter than that of the original ring.